In the joint project PIREF, the metal forming group of the University of Duisburg-Essen has collaborated with the University of Applied Sciences Ruhr-West Mülheim (Ruhr), the University of Siegen, EMG Automation GmbH and SMS group GmbH to develop sensors, for an online measurement of material velocity and cross section as well as control models for the rolling process of wire rod and bars. The University of Duisburg-Essen provided a metal forming process model for the rolling process to assess the influencing parameters on the rolled section precision. A technique was found to segregate height- from width- influencing parameters from a measured cross-sectional area and actual roll gap. With this measuring technology and with help of the process model, rules for control of the rolling process to achieve close tolerances were obtained. The modelling was accompanied by rolling trials on a laboratory rolling mill at the University of Duisburg-Essen, where a typical Round-OvalRound pass sequence was used for validation of the rolling model concerning lateral spread, inlet and outlet velocity as well as rolling force and torque calculation. The present paper shows how the material flow and the distribution of the velocity in the roll gap can be described. In subsequent rolling of bar and rod in a continuous rolling mill the dimensions can be influenced by application of longitudinal stresses and screwdown. The application of stress can be achieved by an inter-stand velocity mismatch. With the developed models the necessary velocity mismatch can be calculated. © ESAFORM 2021 - 24th Inter. Conf. on Mat. Forming. All rights reserved.

The present work aims at the modelling and simulation of the hot rolling process for wire rod and bars. After the fundamentals of plasticity, which are essential for the understanding of the process characteristics have been described, typical section deviations that can be expected in wire rod and bar mills are calculated with help of a numerical simulation model. The model allows the calculation of section shapes under the influence of elastic rolling stand deformations and interstand tensions. From this computational assessment of section faults, the necessity of inline measurement and process control for wire rod and bar mills is shown. This work is part of the PIREF project which incorporates the development of sensors, control systems and process models in order to control the dimensional accuracy of hot rolled wire rod and bars. The metal forming process model, as described here is used internally as a model for the static and kinematic interactions in the rolling process inside of the control model. © 2020 Walter de Gruyter GmbH, Berlin/Boston.

The growth of global population is no longer exponential, but there is still a growth. Are stronger raw materials consumptions automatically the effects? Markets for listed commodities are very much influenced by futures in their pricing, and in a time of comprehensive, extremely fast communication trends and hypes are generated. At the end of the day, markets are determined by the real relationship between supply and demand from a medium- and long-term perspective. What will be the effects in future developments of global commodity markets when China's economy will perform the transformation from an industrial into a service society?. © 2020, Wiley-VCH Verlag. All rights reserved.

The objective of this study was to analyze the recycling possibility of the electric arc furnace dust (EAFD) in the form of a briquette. This paper studied the kinect behavior of the briquette's self-reduction and in contact with molten steel (steel-briquette system) and it was aimed at finding the optimal briquette composition used to recover elements such as Cr, V and W. Thermodynamic simulations with FactSage were carried out to validate the experimental results. The EAFD material as-received was magnetically separated to the form of a magnetic electric arc furnace dust (MEAFD) then characterized analytically and microstructurally. Analytical characterization demonstrated that the EAFD was rich in Cr, W and V. Microstructural analyses revealed the presence of oxides and spinel phases. Three different compositions of briquettes were prepared for the experiments: the first with 84% of MEAFD and 16% C; the second with 82% of MEAFD and 18% C; and the third with 80% of MEAFD and 20% C. Reduction experiments at the temperature of 1500 °C were carried out to study the reduction rate differences in the briquettes and the steel-briquettes systems. Reduction experiments showed that the fastest reaction occurred in the briquette with 20% C for both systems. Among the wide experimental dataset analyzed, the optimal measured recovery was 48.1% Cr, 72.7% W and 47.5% V (in wt%). © 2020

Liquid metal embrittlement (LME) is a phenomenon where a liquid metal damages a solid bulk metal. Notwithstanding previous investigations, LME remains an actual as well as a still not fully understood topic. A so far not yet investigated area can be defined with ultra-high strength austenitic stainless steels for passenger cars. The most commonly used joining procedure in car body engineering is still resistance spot welding. During this vehicle assembly step, the uncoated surface of an austenitic stainless steel is because of the process-related lap joint configuration in direct contact with zinc-coated surface-finished steels as a dissimilar material combination. During welding, liquid zinc could penetrate inside the intermediate sheet zone in the grain boundaries of the austenitic steel and is therefore able to initiate cracks in the heat-affected welding zone. Herein, the radiographic inspection is introduced, which is a process-reliable, nondestructive detection method for the inaccessible intermediate sheet zone area, which is usable in automotive big-industrial scale. With the implemented detection method, liquid metal-induced cracks can be detected in the intermediate sheet zone down to a crack length of 50 μm. Subsequently, the radiographic inspection helps to analyze the crack characteristic depending on surrounding conditions and welding parameters. © 2020 Wiley-VCH GmbH

This study investigates the effect of heat treatment temperature on the properties of charcoal composite pellets used for the reduction of ferroalloys. The heavy fraction of biooil was used as a binder for the charcoal ore pellet preparation. The effect of heat treatment temperature on the pellet shrinkage was related to the degree of reduction which varied with feedstock and ore composition. The results showed that the size and shape of the charcoal pellets were not affected by the biooil devolatilization. Manganese charcoal pellets showed higher electrical resistance during pyrolysis, whereas the structure, composition and electrical resistance of silica composite pellets remained unaffected by heat treatment temperatures [Formula presented] 1650 °C. However, the secondary heat treatment decreased the CO2 gasification reactivity and electrical resistivity of charcoal composite pellets. In addition, the findings of this work demonstrate the potential for using biooil as a binder for the charcoal composite pellets used in ferroalloy industries. The composite pellets are suitable to pre-reduce the manganese ore in the low temperature zones of an industrial furnace, and the charcoal pellets can be used as an alternative bed material. However, the high CO2 reactivity may create challenges during the direct replacement of metallurgical coke with the bio-reductants. © 2019 Elsevier Ltd

This study reports the effect of feedstock origin, residence time, and heat treatment temperature on CO2 and O2 reactivities, nanostructure and carbon chemistry of chars prepared at 1300, 1600, 2400, and 2800 °C in a slow pyrolysis reactor. The structure of char was characterized by transmission electron microscopy and Raman spectroscopy. The CO2 and O2 reactivity of char was investigated by thermogravimetric analysis. Results showed that the ash composition and residence time influence the char reactivity less than the heat treatment temperature. The heat treatment temperature and co-pyrolysis of pinewood char with biooil decreased the CO2 reactivity, approaching that of metallurgical coke. Importantly from a technological standpoint, the reactivities of char from high temperature pyrolysis (2400–2800 °C) were similar to those of metallurgical coke, emphasizing the importance of graphitizing temperatures on the char behavior. Moreover, graphitization of chars from wood and herbaceous biomass increased with the increasing heat treatment temperature, leading to formation of graphitizing carbon. © 2018 Elsevier Ltd

The aim of this work was to study the use of slags to desulfurize cast iron. It was proposed to use alumina instead of fluorspar. In addition, marble waste was used instead of lime. Simulations applying Thermo-Calc® software were carried out in order to obtain the theoretical phases using thermodynamic data. Then, a comparison between theoretical data and experimental tests were performed. Cast iron was melted in induction furnace at 1550ºC. Slags composed mainly for CaO and Al2O3 were used to desulfurize cast iron. The results showed that the desulphurization reaction was favored when the liquid phase was increased. Furthermore, it was found that cast iron desulfurization occurs by top slag mechanism. Furthermore, the desulfurization tests showed a decrease up to 90.10% in the sulfur content to the mixture containing conventional lime and 87.25% to the mixture RMF15. The slags obtained from marble waste contained MgO, which it interfered negatively in the desulfurization yield. In addition, increasing the CaO particle diameter improved the desulfurization process. The desulphurization process more favored to particle size of 500-1000 µm.

This paper addresses a continuum-mechanical, bi-phasic, two-scale numerical model for casting and processing of metallic alloys. The solid and liquid physical states, which represents the solid and molten alloy, are formulated in the framework of the theory of porous media (TPM) including thermal coupling, finite plasticity superimposed by a secondary power creep law and visco-elasticity associated by Darcy's permeability for the solid and the liquid phase, respectively. In view of phase transition during solidification, a two-scale approach considering the phase-field on the micro-scale is proposed, where a double-well potential with two local minima for completely solid and liquid physical states is utilized. The finite element method based on the standard Gallerkin element formulation and the finite difference method was employed for the macro-scale and the micro-scale, respectively. Finally, the performance of the discussed model is demonstrated by the recalculation and validation of a solidification experiment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Nowadays there is a growing interest in studying the influence of primary austenite structure and the formation of graphite particles during solidification to correlate with the formation of microshrinkage or even shrinkage defects on castings. In order to obtain information on the development of the dendritic structure, advanced thermal analysis techniques were applied in the study of hypoeutectic and close eutectic melt compositions to determine the occurrence of the dendritic coherency point (DCP). The occurrence of the DCP has a major importance on metal yield through the design of the in-gate and feeding system of a casting as it determines the available time for feeding and take advantage of the internal expansion inside the mould cavity due to graphite precipitation. To correlate the thermal analysis results and the solidification sequence of the metallographic constituents to identify the occurrence of the DCP, quenching of the thermal analysis sample during solidification was performed to freeze the solidification process at a given characteristic stage of the solidification curve. This has allowed the observation of the stable solidification structure that has developed until the time of quenching. The work performed allowed a better understanding of the solidification structure of hypoeutectic nodular cast iron melts and the occurrence of the dendritic coherency point. © 2017 Portuguese Society of Materials (SPM)

Today the global raw material markets are more volatile due to oligopolistic market structures in certain areas. The price increases in rare earth elements are dramatic, but price increases in certain often used industrial metals are similar, because the development is influenced by the same market mechanism. Recycling processes that were not economical in the past are pushed today by increasing prices. Steel and cast iron recycling processes in closed loops are already realized today. More complicated processes are necessary, if valuable metals are contained in waste materials in low concentration, because more complex problems need to be solved. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.