Abdellah Kharicha

Montanuniversität Leoben · Department Metallurgy

The animation shows streamlines of flow overlaid on the contour of normalized concentration, magnitude and streamlines of normalized current density, and normalized equipotential surfaces overlaid on the contour of normalized electric potential. The transient nature of the simulation provides additional insight into deposition behavior as the evolv...

A numerical model utilizing the volume of fluid (VOF) method is proposed to simulate the transient shape change of the deposit front considering the diffusion-limited electrodeposition process. Modeling equations are proposed to accurately handle transport phenomena in both electrolyte (fluid) and deposit (solid). Transient evolutions of field stru...

The surging demand for large high-quality rotor shafts or similar steel components in heavy industries (energy sector) poses new challenges to steelmakers. Based on the experience of conventional ingot and continuous casting, several new process concepts have been proposed, e.g., vertical continuous casting (VCC), semi-continuous casting (SCC), and...

Clogging of submerged entry nozzle (SEN) during continuous casting of steel is an undesirable phenomenon leading to different problems like flow blockage, slag entrainment, nonuniform solidification, etc. A transient numerical model for nozzle clogging based on an Eulerian-Lagrangian approach was developed and it covers the main steps of clogging:...

Previously, the authors have used a mixed columnar-equiaxed solidification model, successfully ‘reproduced’ the solidification benchmark experiments on the Sn-10wt.%Pb alloy under natural/forced convections (travelling magnetic stirring) as performed at SIMAP laboratory [ Int. J. Heat Mass Transf . 85 ( 2015) 438-54]. The current contribution is to...

Freckles, a significant issue encountered during the directional solidification of superalloys, are recognised by a trail of equiaxed grains parallel to the direction of gravity accompanied by local eutectic enrichment. In the current study, a mixed-columnar-equiaxed multiphase volume-average solidification model was employed to study the formation...

The thin slab casting (TSC) of steel is a type of the continuous casting (CC) with a narrow funnel-shaped mold, characterized by the rapid solidification and fast production rates. A highly turbulent flow impacts on a growing solid shell due to the constant feeding of the fresh hot melt. That strongly affects the solidification profiles and final q...

A series of solidification benchmark experiments based on Sn-10wt.% Pb alloy were performed at the SIMAP Laboratory in Grenoble, France (Hachani et al., 2015) to study the effect of different types of forced convection on the as-cast structure and macrosegregation. Forced convection was achieved by using a traveling magnetic field (TMF). Four cases...

Complex multi-phase phenomena, including turbulent flow, solidification, and magnetohydrodynamics (MHD) forces, occur during the continuous casting (CC) under the applied electromagnetic brake (EMBr). The results of the small-scale experiment of the liquid metal model for continuous casting (mini-LIMMCAST) at the Helmholtz-Zentrum Dresden-Rossendor...

The use of freeze linings to protect pyrometallurgical furnaces from chemically corrosive molten slags is a widespread technique in industrial processes. The main goal of the present study is to establish a modeling framework that considers fluid flow, heat transfer, and slag solidification to simulate freeze-lining formation and its dependency on...

The high-speed camera (Phantom v2512) is used to capture behaviors of arc plasma in an industrial VAR process. A recording rate of 60000 frames per second (60k fps) for this video is used. We observed a fairly symmetrical and centric plasma column during the operation.

The high-speed camera (Phantom v2512) is used to capture behaviors of cathode spots in an industrial VAR process. A recording rate of 60000 frames per second (60k fps) for this video is used. We observed that spots prefer to onset and remain within the partially melted surface at the center of the electrode tip. Existing spots outside the melting z...

Inhomogeneous distribution of the eutectic phase in single crystal (SC) turbine blades is detrimental to its mechanical properties. In a recent publication, it was reported that an accumulation of eutectics was observed on the upper surface of solidification units (e.g. shroud of a turbine blade), whereas fewer eutectics were detected at the bottom...

Continuous casting (CC) became one of the dominant steel production technologies throughout last decades. Better quality, energy savings and high production rates are the main aims of the research especially in the field of the thin slab casting (TSC). The electromagnetic brake (EMBr) is applied to control the highly turbulent flow after the fresh...

Single-crystal superalloy turbine blades (TBs) fabricated using directional solidification are key components of aeroengines and gas turbines. Owing to thermal–solutal convection during solidification, such components are susceptible to flow-induced defects such as freckles and/or eutectic accumulation. The formation mechanisms of the above defects...

In article 2200088, Kharicha and co-workers show that a uniform melt motion is vital for the thin slab casting process featured by the high casting and solidification rates. Here an application of electromagnetic braking to suppress an asymmetric flow is illustrated. The induced electric current lines, generated around the jets, tend to close throu...

In the present study, we investigate arc plasma expansion in an industrial vacuum arc remelting (VAR) process using experimental and numerical tools. Stainless steel is the alloy of interest for the electrode (cathode) and ingot (anode). During the operation of the VAR process, behaviors of cathode spots and plasma arc were captured using the high-...

Due to the extreme thermal conditions and short lifetimes, experimental exploration of cathode spots in vacuum arcs is very difficult. The intensive heat in the cathode spot is believed to be generated by ion bombardment and by Joule heating. However, thermal conditions occurring inside the re-melted material in craters created by cathode spots are...

When a strand is subjected to rolling and pressing during mechanical reduction (MR), deformation-induced strand contraction or dilatation can occur. A novel modelling strategy has been designed to account for this mechanism in a two-phase Eulerian–Eulerian volume-average model with a fixed geometry. The strategy is based on the following ideas: 1)...

Forced convection and its effect on the microstructure evolution of an Al-7wt.%Si alloy during unidirectional solidification were studied experimentally. Under natural convection (gravity), columnar structures develop. However, under forced convection by activating a rotating magnetic field (RMF: 10 mT, 50 Hz), many equiaxed grains form in the half...

In the Electroslag Remelting (ESR) process, the electrode tip is plunged into the slag bath. Its immersion depth is a key parameter that has a strong influence on electromagnetic phenomena and coupled transfers within the slag. Associating trial remeltings and numerical modeling of the process, some specific impacts of electrode immersion depth are...

A two‐phase solidification model coupling mold electromagnetic stirring (M‐EMS) was used to investigate the initial solidification in the mold region of billet continuous casting. One novelty of this numerical study is to quantify how the M‐EMS induces primary and secondary flows, interacting with the jet flows coming from the submerged entry nozzl...

Animation- Diffusive Arc under an Axial magnetic Field in VAR process

Animation- Rotating Arc under an Axial magnetic Field in VAR process

Animation- Eccentric Arc under an Axial magnetic Field in VAR process

Animation- Centric Arc under an Axial magnetic Field in VAR process

A numerical model coupling electromagnetic field and plasma arc impact with multiphase transport phenomena such as flow, heat transfer and solidification for the vacuum arc remelting (VAR) process is proposed. 3D simulations of the VAR process for refining a Titanium-based (Ti-6Al-4V) alloy are made. Different arc distributions (diffusive, constric...

A mixed columnar-equiaxed solidification model was recently extended to capture the capillary-driven fragmentation phenomenon, which was considered the only mechanism for the formation of equiaxed crystals. The purpose of the present study was to validate the model by replicating a laboratory experiment on the solidification of an aqueous ammonium...

These supplementary results show the instability of the flow inside a thin slab casting mold when the submerged entry nozzle is under moderate one-side clogging. No electromagnetic braking is applied. For the details please refer to the original paper: Vakhrushev et al.: Modeling Asymmetric Flow in the Thin‐Slab Casting Mold Under Electromagnetic...

These supplementary results show the effects of the applied electromagnetic braking on the flow inside a thin slab casting mold when the submerged entry nozzle is under moderate one-side clogging. For the details please refer to the original paper: Vakhrushev et al.: Modeling Asymmetric Flow in the Thin‐Slab Casting Mold Under Electromagnetic Brak...

These supplementary results show the effects of the applied electromagnetic braking on the flow inside a thin slab casting mold when the one-side clogging of the submerged entry nozzle is quite low. For the details please refer to the original paper: Vakhrushev et al.: Modeling Asymmetric Flow in the Thin‐Slab Casting Mold Under Electromagnetic Br...

These supplementary results show the effects of the applied electromagnetic braking on the flow inside a thin slab casting mold when the one-side clogging of the submerged entry nozzle is fully blocking. For the details please refer to the original paper: Vakhrushev et al.: Modeling Asymmetric Flow in the Thin‐Slab Casting Mold Under Electromagnet...

Electromagnetic stirring (EMS) has been recognized as a mature technique in steel industry to control the as-cast structure of steel continuous casting (CC), and computational magnetohydrodynamic (MHD) methods have been applied to study the EMS efficiency. Most MHD methods de-coupled the calculations of electromagnetic and flow fields or simplifica...

Continuous casting is nowadays the world‐leading technology for the steel production. The thin slab casting (TSC) is featured by a slab shape close to the final products, which are casted at a high speed with the fast solidification rate. The quality of the thin slabs strongly depends on the uniformity of the turbulent flow, the super‐heat distribu...

This course held in English is designed for students, engineers and scientists from industry and research centers who wish to improve their knowledge in the field of applied Magneto-hydrodynamics. Although the theoretical background of MHD is reviewed, the course is mainly oriented towards the numerical methods and application to industrial process...

Contains correct affiliations of the authors.

A funnel-type mold is commonly used to provide necessary clearance for the submerged entry nozzle in the thin slab casting (TSC). The partially solidified shell is subjected to the mechanical deformations, which can lead to the defects formation and, as a results, to a breakout. Traditionally, the results of the flow simulation, performed by the fi...

A numerical analysis is carried out to explore the variety of flow structures induced inside a conducting fluid emerging from the interaction of an electric current source with an external axial magnetic field. Results are obtained for Shercliff (S) numbers up to 10¹⁰ and Hartmann (Ha) numbers up to 115, for a single magnetic Prandtl number of Pm=8...

In this paper we show that the presence of liquid flow around a crystal growing by precipitation can induce dissymmetry in growth similar to that described by anisotropic interfacial kinetic coefficients. A front tracking interface model based on a cellular automaton approach was applied to the growth of a Fe2Al5 crystal (also known as top dross pa...

Turbulent jet flow under the applied transversal magnetic field at Reynolds number Re=850 and interaction number N=0.05. Displays the distribution of the induced electric field at the parallel to the magnetic field plane (top), magnitude of velocity (left) and the rotation direction (middle and right) on the corresponding vortical structures.

Turbulent jet flow under the applied transversal magnetic field at Reynolds number Re=2700 and interaction number N=0.05. Displays the distribution of the induced electric field at the parallel to the magnetic field plane (top), magnitude of velocity (left) and the rotation direction (middle and right) on the corresponding vortical structures.

Turbulent jet flow under the applied transversal magnetic field at Reynolds number Re=4050 and interaction number N=0.05. Displays the distribution of the induced electric field at the parallel to the magnetic field plane (top), magnitude of velocity (left) and the rotation direction (middle and right) on the corresponding vortical structures.

Magnetohydrodynamic instability in a high-intensity arc, similar to typical arcs in DC electric arc furnaces, is simulated using an induction based model under 2D axisymmetric conditions. Time-averaged results show a good agreement with steady-state calculated results expected for a stable arc. The transient results declare that z-pinch close to th...

Simulation in Werkstoffwissenschaft: Vakhrushev A, Kharicha A, Liu Z, Wu M, Ludwig A, Nitzl G, Tang Y, Hackl G, Watzinger J, Electric Current Distribution During Electromagnetic Braking in Continuous Casting. Metall. Mater. Trans. B 2020, 51, 2811–2828, https://doi.org/10.1007/s11663-020-01952-3

During the last decade, the chair for ‘Simulation and Modelling of Metallurgical Processes’ (SMMP) has worked on different metallurgical processes with the highlights of the following five industrial relevant topics: (i) modelling the as-cast structures of large steel castings; (ii) exploring the formation mechanisms of macrosegregation; (iii) desc...

Spatial evolution of electrically conducting submerged jet flow is studied by numerical simulations for the case of a transverse uniform magnetic field. This situation occurs frequently in metallurgical industry where permanent magnetic fields are applied to control the liquid metal jets. We investigate through numerical simulations the flow charac...

Transport phenomena including the electromagnetic, concentration of ions, flow, and thermal fields in the electroslag remelting (ESR) process made of slag, electrode, air, mold, and melt pool are computed considering tertiary current distribution. Nernst-Planck equations are solved in the bulk of slag, and faradaic reactions are regarded at the met...

Mold electromagnetic stirring (M-EMS) has been introduced into the continuous casting of steel billets to promote the formation of a central equiaxed zone; however, the formation mechanism of the equiaxed crystals and the effect of M-EMS on crystal transport are not fully understood. Currently, a three-phase volume average model was used to study t...

A fully coupled model is proposed to investigate the influence of flow on electrochemical mass transfer at the interface between the electrolyte and an electrically conductive droplet. The electric current flows through the droplet, and consequently the droplet acts as both anode and cathode. Computations of flow, concentration of reactant, and ele...

The clogging of the submerged entry nozzle (SEN) during the continuous casting of steel can be divided into two stages: the “early stage,” when the initial layer of the clog covers the SEN refractory surface owing to chemical reactions, and the “late stage,” when the clog layer continues to grow because of the deposition of non-metallic inclusions...

A 2D axisymmetric two-phase model was developed to study the effect of an arc impingement on the liquid metal inside an electric arc furnace. In addition to the arc flow dynamics, the model covered the heat transfer and magneto hydrodynamics of the arc and the liquid metal. Through a parametric study, three different parameters were considered to p...

Cover Story (https://www.mdpi.com/2075-4701/11/9): The heat losses in the submerged entry nozzle (SEN) region were investigated using a novel numerical approach by coupling the convection and heat transfer in the liquid slag and melt pool. It was revealed that the parasitic solidification occurred inside an SEN bore with partially or completely abs...

Continuous casting (CC) is one of the most important processes of steel production; it features a high production rate and close to the net shape. The quality improvement of final CC products is an important goal of scientific research. One of the defining issues of this goal is the stability of the casting process. The clogging of submerged entry...

In this study, a first attempt is made to bridge capillary-driven fragmentation and grain transport using a mixed columnar-equiaxed solidification model. Grain transport is an intrinsic feature of the employed solidification model which has been extensively investigated over the years. Regarding the capillary-driven fragmentation event, a new corre...

This animation shows poloidal and toroidal velocity field in the melt pool of VAR process considering a time-varying axial magnetic field (AMF) with ten seconds for the reversal time of the direction of magnetic field. The article and the animation are also available in: https://link.springer.com/article/10.1007/s11663-021-02264-w

Detailed description of the animated supplementary results for the paper: Vakhrushev, A., Kharicha, A., Karimi-Sibaki, E. et al. Generation of Reverse Meniscus Flow by Applying An Electromagnetic Brake. Metall Mater Trans B (2021). https://doi.org/10.1007/s11663-021-02247-x

Simulation results of the turbulent flow under the applied EMBr of 156 mT showing the distribution of the induced electric current, velocity field and the turbulent structures (defined by the iso-surface Qcrit=100). The flow alternation is significant: turbulence is mostly damped; corresponding redistribution of the linear momentum causes accelerat...