Seznam abstraktů 2025: SEKCE A - POKROKOVÉ TECHNOLOGIE VÝROBY ŽELEZA, OCELI A VE SLÉVARENSTVÍ

Due to large variety of chemical compositions, structure states and related properties, steel has become the most widely used metallic material. However, under some conditions its far from being excellent, such as in the case of high-temperature applications. Moreover, for specific steel grades, like tool steels, the addition of critical raw materials (vanadium, tungsten, cobalt) is needed. These problems can be potentially solved by the substitution of steel by intermetallics in specific cases. The solution for high temperatures can be the use of iron or nickel aluminides, where iron aluminide-based materials started to be used already in 1950’s and underwent significant development till present days. In the case of tool materials, the solution could be found in the case of intermetallic composites, which are now under development. History of the development of these materials and several selected case studies of the use of intermetallics instead of a steel are included in the lecture.

This research was financially supported by Czech Science Foundation, project No. 23-05126S

This study explores the application of Dense Optical Flow (DOF) technique to investigate fluid dynamics in physical water models of tundish and mold systems, used in continuous casting processes. DOF methods, traditionally employed in computer vision for object flow speed estimation, are adapted to analyze the velocity fields and flow patterns in real-world water-based physical models, offering a low-cost and accurate approach to visualize complex flows. By capturing video footage and processing the frames using DOF algorithm, detailed insights into flow structures, velocity map is obtained. This approach enables a deeper understanding of the impact of various parameters, such as inlet velocity and geometric configurations, on the overall flow dynamics. The results demonstrate the potential of DOF to generate datasets containing information about fluid dynamics for further analysis.

The quality of titania slag has been largely investigated using coke. However, the environmental threats caused by carbon emissions has opened a platform to investigate the use of other reductants and their impacts on the slag quality. The aim of this investigation is to correlate the impact of hydrogen used as reductant in the pre-reduction of ilmenite on the quality of the titania slag. Reduction is a pyro-metallurgical process where metal is extracted from its ore by heating and melting it at elevated temperatures in a furnace with the addition of fluxes and reductants. In this research paper hydrogen was used as reductant during prereduction of ilmenite. Argon was concomitantly blown in with hydrogen to dilute the explosive effect of hydrogen at high temperatures. A thermogravimetric analyser (TGA) was used to perform experiments at 800, 900 and 1000 ℃. The aim of using hydrogen was to assumably increase the rate of reactions. The good quality titania slag in the pre-reduced sample must contain high iron, low Ti2O3, high TiO2 and high mass loss. The optimal concentration of hydrogen was investigated firstly through prediction using Fact sage and confirmedsecondly through TGA test. The fact sage predictions and TGA tests aligned well with one another. The optimal conditions for the prereduced ilmenite, were found to be 50:50 for the Ar:H2 ratio at 1000℃ for 180 minutes.

The sintering process is a process in which various raw materials such as fine iron ores, return fine ore, limestone, and fine coke or anthracite as solid fuel are mixed and granulated together with moisture, and then the mixed raw materials are loaded into the sintering machine, ignited in an ignition furnace, and the solid fuel is combusted by the air sucked in downwards to produce iron ore sinter used in the blast furnace process. In the iron ore sintering process, securing permeability so that an appropriate amount of air can pass through the mixed raw material layer in the sintering machine and flow smoothly from top to bottom is a very important factor that affects the progress of the combustion zone and the sinter productivity.
Moisture control is very important for the granulation and air permeability of the mixed raw materials. When there is insufficient moisture for the granulation, the mixed raw materials is poorly granulated, and when there is too much moisture, the moisture condensation zone at the bottom of the mixed raw material layer becomes more severe, which reduces the permeability. In both cases, it is the main cause of reducing sintering productivity.
The water holding capacity of each type of iron ore was measured, and the optimal granulation moisture of return fine ore, limestone, and solid fuel was derived through a permeability test to obtain the appropriate granulation moisture of the mixed raw materials. Using this, the optimal granulation moisture according to the type and mixing ratio of the raw materials could be derived.
In order to control the real-time optimal granulation moisture considering the type and mixing ratio of the raw materials, the system was built to automatically control the additional moisture amount according to the difference between the real-time moisture of the mixed raw materials measured by the microwave online moisture analyzer and the optimal moisture content. When this system was applied to the sintering plant, it was confirmed that productivity increased and the fuel ratio reduced

Reducing width deviation through slab width control of 400 series stainless steel can reduce edge defects in hot-rolled products, thereby promoting yield improvement, which is a very important technology. This technology has been applied to the online process using an AI-based MLP (Multi-Layer Perceptron) model. This model collects width data and casting operation data at 1-second intervals during continuous casting. In the data preprocessing stage, it is essential to arrange the operation data according to the position of the slab within the caster. The developed width control model provides basic data for real-time cooling control and showed over 95% accuracy in predicting the final slab width for both training and evaluation data.

Next generation casting technologies such as thin slab, belt or strip casting have gained popularity due to the reported energy saving, which can be as high as 1.6 GJ/tonne when compared to conventional thick slab casting. However, these casting approaches result in changes in cooling rate during solidification and in thickness reduction to the required product geometry, affecting the resulting microstructure and elemental segregation.
In this work the secondary dendrite arm spacing (SDAS) and micro-segregation levels for the range of cooling rates relevant for different casting technologies (0.8 to 10 °C/s) have been assessed using predicted COMSOL modelling coupled with known empirical SDAS and cooling rate relationships. A dual phase DP800 steel has been selected as the base material with systematic variation of Manganese (Mn) contents to evaluate its specific role in micro-segregation.
SEM-EDX grid maps have been used to characterise micro-segregation levels. To complement the experimental observations, Thermo-Calc simulations were conducted to predict micro-segregation behaviour using both initial cooling rates and post-solidification profiles for validation. The segregation ratios have been mapped for various cooling rates - correlating to the casting relevant techniques enabling quantification of segregation severity. The insights gained offer an understanding of the sensitivity of Mn segregation to cooling rate.

Secondary cooling plays a critical role in the continuous casting of steel slabs, directly influencing surface and subsurface structure dynamics, defect formation, and final product quality. Common methods for controlling secondary cooling water flow include proportional control based on casting speed, real-time adaptive (dynamic) cooling models, and closed-loop feedback control systems.
During non-steady-state casting, some of these methods may introduce undesirable temperature transients, potentially leading to strand defects or even causing the solidified slab to become stuck in the curved section of the casting machine.
To analyze secondary cooling modes in continuous steel slab casting, a mathematical model and relevant software tool were developed. The model is based on nonlinear heat transfer equations and incorporates the Stefan problem to account for phase transitions, enabling accurate temperature distribution predictions across the slab’s longitudinal cross-section.
Finite-difference numerical methods with an explicit scheme solve the governing equations, allowing evaluation of different cooling strategies and their effects on shell temperature, thermal gradients, and crack susceptibility.
The user interface provides casting parameters such as average and maximum heat flow in the mold, surface temperature, and water flow for each section while enabling real-time temperature monitoring through charts and graphs.
Results comparing temperature regime deviations under open-loop, model predictive, and uncontrolled secondary cooling are presented.
The proposed approach serves as an effective tool for steelmakers and researchers to conduct numerical simulations and experiments aimed at optimizing secondary cooling in continuous casting to enhance slab quality.

Roturbo multi-mode meniscus electromagnetic stirring (ROMODE-EMS) in tundish and flow controlling system is the advanced product. The unique magnetic turbo-circuit design and control technology, the product can automatically realize many stirring modes: single/turbo rotation mode, acceleration mode, deceleration mode, two-zone turbo mode, double-helix acceleration mode and so on. By using the metallurgical data packet, the required stirring position, modes and parameters can be switched according to the steel grades, the strand section and the quality requirements. So, electromagnetic stirrer for meniscus is installed on the mold the continuous caster. The strong Multiphysics coupling are studied with heat transfer or Navier-Stokes interface for induction heating or fluid flow control. In the case if the of laminar flow steel depth δ (penetration depth of the electromagnetic field inside the material) is very small compared to the characteristic dimension (e). A surface Impedance is set up and we do not need to resolve in detail the interior volume. Regarding, a thin conductive layer (e < δ), the layer is described only by a surface with a two way boundary condition. The electromagnetic action zone covers the meniscus. Mainly used to improve surface and subsurface quality of the bloom / slab. It is one of the key metallurgical equipment’s for continuous casting of special steel with high surface quality requirements, such as EV-cars and household appliances [1]. Roturbo MODE-Electromagnetic (ROMODE-EMS) processes are good candidates for energy saving and CO reduction demands. In metallurgy industry, it leads to productivity improvement, maintenance reduction and safety integration.

In EAF steelmaking considerable amounts of dust are generated. Depending on the furnace type and the content of organic material in the scrap EAF dust contains beside iron oxides, slag components and zinc also some organic matter (TOC). Recycling of this iron-rich residue is common via briquetting of the EAF dust together with other fine granular steel mill residues and a binder. It is assumed that a higher TOC content in EAF is unfavourable for the strength of the briquettes. In this study, EAF dust was refluxed with an organic solvent (n-heptane) in order to reduce the TOC content of the EAF dust by approximately 50%. Subsequently, both the solvent-leached EAF dust and the untreated original EAF dust were used in mixtures in the production of briquettes in a stamp press. Bentonite, modified starch and a mixture of molasses and hydrated lime were used as binders. The strength of the agglomerates was tested immediately after pressing, one hour and twenty-four hours after pressing. The results showed in most cases a higher strength of the briquettes containing leached EAF dust.

Approximately 1 billion tonnes of ash and slag waste are produced annually from coal-fired power plants worldwide, including 30 million tonnes in Ukraine. The total amount of accumulated ash and slag waste in Ukraine exceeds 360 million tonnes. Their accumulation creates serious environmental risks and economic problems. Many methods based on physical, chemical and combined approaches are known for ash and slag waste disposal. Most often these wastes are used in the production of building and road construction materials. However, ash and slag wastes contain significant amount of metal oxides that can be extracted to form alloys. The total content of Fe, Al and Si oxides in ash and slag waste can reach 60%. However, the instability of the chemical composition is a serious problem in their metallurgical processing. Traditionally, the metallurgical methods for processing these wastes are based on carbon reduction, which involves significant CO2 emissions to the environment. This approach is not in line with the current trend towards decarbonisation of industrial production. To find alternatives, the possibility of using the electrometallurgical smelting process with extraction of metals into an alloy in the recycling chain is being investigated using the ash and slag waste from Trypilska TPP. The aluminium waste is used as a metal oxide reducing agent. Laboratory experiments on the remelting of ash and slag waste by the method of reductive electroslag melting have shown the possibility of implementing a waste processing with the production of iron or aluminium-based alloys at the first stage of recycling.

By recycling metal waste and scrap, industries can follow to the principles of a circular economy, where materials are reused and recycled to reduce waste and resource consumption. However, it is not always possible to process the metal while maintaining its chemical composition and producing high-quality ingots without complicating the technological process and incurring excessive costs. From this point of view, electroslag remelting can be an effective technology for recycling alloyed steel and nickel alloys to produce a high-quality material with reduced environmental impact and minimized toxic emissions. Modern two-circuit ESR technology with a current-supply mould significantly reduces the requirements for the geometry of the consumable electrode and greatly improves the ability to control the thermal processes taking place in the slag and metal bath. The research conducted has demonstrated the ability to effectively recycle various types of metal scrap, from used small tools to nickel alloy fragments, while preserving their chemical composition and producing quality ingots. The experiments also showed significant potential for processing metal chips and other similar metal wastes with production of quality ingots. The presentation reviews the technological aspects and the results of a series of studies on the recycling of various types of alloy steel and nickel alloy waste and scrap using the current-supply mold and two-circuit electroslag remelting technology.

Real-time measurements in steel continuous casting are challenging due to extreme temperatures, leading to limited process understanding and frequent breakouts. This project aims to address this issue of casting process control by simulating steel flow using a low-melting-point Bi-Sn alloy with steel-like properties, enabling real-time analysis of pressure, velocity, vibrations, and mold level fluctuations to optimize stopper-nozzle designs. A novel glass window in the nozzle rod provides unprecedented visibility into liquid metal flow under varying inert gas injection rates. Results from Swerim’s unique Continuous Casting Simulator (CCS), the world’s only facility of its kind, are validated through SSAB plant trials. This innovation drives greater efficiency, fewer breakouts, and a deeper understanding of casting dynamics, marking a transformative leap for the steel industry.