Seznam abstraktů 2024: SEKCE A - POKROKOVÉ TECHNOLOGIE VÝROBY ŽELEZA, OCELI A VE SLÉVARENSTVÍ

The use of continuous casting has been growing steadily since the 1950s. Steel producers, like those in other industries, are still concerned with two important optimization objectives, namely maximizing profits and minimizing production costs. Nowadays, an additional objective is the need to monitor and evaluate environmental aspects. For example, the problem of reducing CO2 emissions in production, conserving water resources, etc. is reflected in the economics of the production and thus represents an additional constraint in optimization calculations. External inputs such as raw material prices, energy market prices and labor costs are generally not controllable, but we can control the process itself. From an economic point of view, there are two main factors to consider in the continuous casting process, namely the casting speed and the quality of the cast steel. The search for the optimum casing parameters can be carried out using advanced digital twins of the casting process, which are usually formed by a combination of the numerical methods, optimization algorithms and a statistical evaluation of the monitoring variables. Nowadays, numerical models are gradually being replaced by so-called surrogate models formed by deep neural networks, which can bring many advantages, but also raise many questions about reliability, accuracy, transferability, robustness, etc. Another important question for any surrogate model is how much training data it needs to find a good enough solution for the user. If it is not possible to collect this data directly from the real casting process, the combination of a verified numerical model which will train the surrogate model seems to be a good way.

The metallurgical aspects typical of this process, the high freezing rate provides an extremely refined solidification microstructure characterized by dendritic ramifications, improves segregation and increases the mechanical properties of metal. The aim of this work is develops the, CastMag Oscillation (CMO) technology. By multiphysics approach which combined fluid dynamics, heat transfer, process metallurgy, solidification, it is possible now to define new innovative processes with the integration of new design of Double-Helix CMO system. Future development of DH-CMO applicability is in agreement with energy savings and CO2 reduction demand. DRI produced at high temp. (> 777°C) with metallization up to 90-95% and controlled carbon ≤ 5%, and which is pneumatically transported from the reactor discharge to the meltshop for direct feeding to the EAF shop. The DRI is capitalized in the EAF. The typical configuration of DR-based EAF steel-shop involves moving bed reduction reactor producing cold discharged direct reduced iron, which could be either stored / sent directly to the electric furnace shop by means of conveyors. The DRI typically has a metallization level of up to 95% and carbon levels in the range of 1.75%-2.3%. The DH-CMO is anti-bulging technology is an innovative solution transforming continuous casting to make it safer, faster, and more reliable. EM processing can be classified by type of magnetic field involved: from AC to DC field. These processes are suitable for heating, melting, flow, shape control, solidification control (stirring, pumping), for each application a specific configuration needs to be defined, selected and optimized continuous-casting

Stainless steel production typically follows the duplex process, beginning with the electric arc furnace (EAF) and proceeding to the vacuum oxygen decarburizer (VOD) or argon oxygen decarburizer (AOD). The EAF's role is to melt the charge and heat it up for further processing, reducing tap-to-tap times through partial oxidation. However, this partial oxidation in the EAF leads to chromium losses as oxygen interacts with the high chromium steel melt. To address this issue, parameters affecting chromium burn-off have been identified and presented. A primary challenge in EAF steel production with elevated chromium content is to lower carbon levels while maximizing chromium yield in the melt. Unlike VOD and AOD processes, which permit low carbon and high chromium levels through vacuum or argon blowing, the EAF provides limited protection, mainly through silicon. At higher temperatures, carbon oxidation predominates, hence it is important to limit oxygen input into the system in the initial stages, while “protecting” the chromium with silicon. During the oxidation phase of the steel melt, carbon content decreases; however, attention must be paid to ensure that the concentration is not too low, as this increases chromium activity in the melt, leading to more intense oxidation. A practical model, derived from thermodynamic calculations, has been developed to guide carbon, chromium, and other element oxidation during scrap melting. This model, validated through industrial trials, aids in optimizing steel melt oxidation to minimize chromium losses effectively.

In the iron and steel industry large amounts of fine granular bulk material like iron ore fines, fluxes, foundry sands or residues from off-gas dedusting have to be handled. In storage, conveying and handling of such materials wall friction between the particles and the wall material is an important parameter. Recently, it was demonstrated that coatings made of diamond-like carbon (DLC) applied on the surface of the wall material can reduce the wall friction angle with fine granular bulk material substantially. In this study, wall friction angles of different wall materials with various fine granular bulk materials from steel mills were investigated. The results showed a significant reduction of the wall friction angle by the DLC coating in comparison to uncoated steel of up to more than 10°, while other coatings showed comparatively little reduction in wall friction.

The race against time towards carbon neutrality has driven several countries to adopt large-scale use of green hydrogen, with Germany aiming to reach 10 GW-scale electrolysis capacities by 2030. This planned industrialization will yield significant waste streams in the form of end-of-life electrolysis and fuel cells. To support decarbonization efforts, we explored the resource recyclability of metallic components, specifically interconnect assemblies, in an end-of-life JÜLICH SOC stack. While an interconnect assembly is primarily constituted of ferritic steel substrate, it also contains additional layers in the form of oxide coatings, oxidation products, glass sealants and welded nickel meshes, all of which considerably impact the overall composition. Extensive characterization studies revealed the potential of interconnect assemblies as raw material in the production of AISI 3xx austenitic stainless steels. Therefore, an open-loop recycling route based on scrap-based steelmaking operations was proposed and evaluated. This included pre-treatment stages to control contamination levels, as well as metallurgical smelting, refinement and heat treatment processes to achieve target alloy composition and microstructure. Results demonstrated successful production of austenitic stainless steel with less than 4 % delta-ferrite. Furthermore, tramp elements were effectively managed within their tolerance limits. Finally, high temperature X-ray diffraction (HT-XRD) experiments showed valuable insights into the austenite stability regions of recycled steels, while micro-indentation tests confirmed hardness values comparable to commercial-grade steels.

Today, Li-ion batteries (LIBs) play a vital role in reducing the consumption of fossil fuels. With the increasing production of LIBs, it is crucial to consider their recycling after reaching their end-of-life. Pyrometallurgy is a technique that can be employed for the recycling of LIBs, which deals with the formation of three phases: melt, slag, and gas. In-situ alloying by the addition of hematite to the LIB black mass was studied previously by the authors. The effect of CaO-SiO2 slag composition on the aforementioned system has been investigated in this work. The CaO:SiO2 mass ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 were tested in that system at a temperature of 1450 °C. Thermodynamic modelling with FactSage 8.0 supported the experimental work. From this qualitative study, it can be anticipated that by increasing the SiO2 amount, metallics coalesce more effectively, the probability of melt/slag separation increases, and Li gasification is enhanced. The addition of CaO may result in the entrapment of Li within the Ca silicate structure and lower its gasification. Thermodynamic calculations revealed a consistent trend in the distribution of Li and F as the CaO:SiO2 ratio changed, suggesting the potential formation of gaseous compounds such as LiF.

This article deals with thermal inserts in injection molds and their effect on the mechanical properties of crystalline plastics. A description of injection molding technology, injection molding technological conditions and their effect on injection properties, methods of tempering injection moulds, temperature field in the injection mould, methods of temperature measurement are provided. At the end, methods of evaluating the mechanical properties of crystalline thermoplastics are presented. The measurement of temperature fields in an injection mold containing thermal inserts is also performed.

Nowadays, steelmaking companies use numerical simulations as an advanced tool to optimize process parameters, reduce defects, and enhance product quality, aligning with the rising market demand for high-quality steel ingots. For more accurate simulations, it is essential to set the correct material properties, process parameters (such as flow rate and temperatures), heat transfer coefficient, as well as the suitable geometry and corresponding discretization. During the mold filling, one main issue is the trapping in the liquid of casting powders used to protect the steel from reoxidation, which turns in the presence of large non-metallic inclusions in the solidified part and the consequent discard. This work is part of an industrial research aimed at studying the filling and solidification of a 26-ton square ingot by using numerical simulation with the commercial program ProCAST®. The study investigates the impact of several casting parameters and liquid upgate system geometries on the creation of exogenous non-metallic inclusions through simplified numerical simulations. The reliability of the simulation model was evaluated by an experimental test conducted on an industrial scale:
the inclusions measured were all less than the acceptable threshold of <2.0 mm equivalent defect. The research was able to establish the conditions needed to prevent the sporadic entrapment of casting powders, hence enhancing the overall quality of this type of ingot.