AG der Dillinger Huttenwerke

Dillingen an der Donau, Germany

AG der Dillinger Huttenwerke

Dillingen an der Donau, Germany
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Eisenhut L.,Saarland University | Rupp D.,AG der Dillinger Huttenwerke | Motz C.,Saarland University
TMP 2016 - 5th International Conference on ThermoMechanical Processing, Advance Programme | Year: 2016

In order to model the grain growth behavior of austenite in the austenitisation phase of the thermomechanical processing, different microstructures were produced for different micro-alloyed steels by varying annealing temperatures and times and finally water quenching. To solve the challenging task of determining the prior austenitic structure, including the grain size distribution, three different methods were applied: Chemical etching, thermal etching and EBSD measurements. All methods were compared in respect to their applicability, reliability and accuracy. The grain size distributions of the different microstructures were used as the basic information for the comparison to a microstructural model for the prediction of the austenitic grain growth during the austenitisation phase of C-Mn micro-alloyed steels. Such a modelling is necessary because the existing models are often empirical or semi-empirical, only derived for special steel grades and thus only applicable to them. The application of the evolution of such a microstructural model on the experimental data is depicted. © 2016, ThermoMechanical Processing (TMP). All rights reserved.

Hegetschweiler A.,Leibniz Institute for New Materials | Staudt T.,AG der Dillinger Huttenwerke | Kraus T.,Leibniz Institute for New Materials
TMP 2016 - 5th International Conference on ThermoMechanical Processing, Advance Programme | Year: 2016

We extracted carbonitride nanoparticles from thermomechanically rolled steels and studied the influence of different etchants on the extracted particles. Elementary analysis, transmission electron microscopy, and light scattering were used to analyze particle dissolution, particle size and particle shape depending on acid type and concentration. Both niobium and titanium carbonitride particles were attacked by the etchants. While the niobium carbonitride particles were sensitive to acid type and concentration, titanium carbonitride particles were similarly attacked by all etchants. A silicate network formed during etching that embedded the target particles and impeded the analysis of them. We found that the silicon concentration in the etchant strongly affects silicate formation while acid type and concentration had only minor influences. © 2016, ThermoMechanical Processing (TMP). All rights reserved.

Hecht M.,AG der Dillinger Huttenwerke GmbH
Stahl und Eisen | Year: 2017

The idea of Industrie 4.0 and its connected activities and technologies have started increasingly influencing both industrial production in general and also the steel industry. For the manufacturing industry the way to the realization of Industrie 4.0 is clearly visible, since there are plenty of examples in literature, television and internet. In contrast, for the steel industry it still has to be elaborated which ideas and solutions are practically applicable, how the topic can be tackled systematically in general and how it can be introduced into the business processes. AG der Dillinger Hüttenwerke (Dillinger) started the systematic transformation into an Industrie 4.0 company last year. The present paper describes the first steps and experiences.

DiRienzo A.L.,University of Wyoming | Yakacki C.M.,University of Colorado at Denver | Frensemeier M.,Leibniz Institute for New Materials | Schneider A.S.,AG der Dillinger Huttenwerke | And 3 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2014

The focus of this study was to fabricate and investigate the mechanical behavior of porous poly(para-phenylene) (PPP) for potential use as a load-bearing orthopedic biomaterial. PPPs are known to have exceptional mechanical properties due to their aromatic backbone; however, the manufacturing and properties of PPP porous structures have not been previously investigated. Tailored porous structures with either small (150-250. μm) or large (420-500. μm) pore sizes were manufactured using a powder-sintering/salt-leaching technique. Porosities were systematically varied using 50 to 90. vol%. Micro-computed tomography (μCT) and scanning electron microscopy (SEM) were used to verify an open-cell structure and investigate pore morphology of the scaffolds. Uniaxial mechanical behavior of solid and porous PPP samples was characterized through tensile and compressive testing. Both modulus and strength decreased with increasing porosity and matched well with foam theory. Porous scaffolds showed a significant decrease in strain-to-failure (<4%) under tensile loading and experienced linear elasticity, plastic deformation, and densification under compressive loading. Over the size ranges tested, pore size did not significantly influence the mechanical behavior of the scaffolds on a consistent basis. These results are discussed in regards to use of porous PPP for orthopedic applications and a prototype porous interbody fusion cage is presented.© 2013 Elsevier Ltd.

Steinboeck A.,Vienna University of Technology | Graichen K.,Vienna University of Technology | Wild D.,AG der Dillinger Huttenwerke | Kiefer T.,AG der Dillinger Huttenwerke | Kugi A.,Vienna University of Technology
Journal of Process Control | Year: 2011

A temperature control method is developed for reheating steel slabs in an industrial furnace. The work was motivated by the need for mathematically simple furnace control schemes that feature accuracy, robustness, applicability to online control, and capabilities of non-steady-state operating scenarios, where the temperature goals and other properties of the slabs may vary considerably. The proposed hierarchical control concept computes desired heat inputs for each individual slab based on a discrete-time nonlinear model. Then, a quadratic program is solved to plan reference trajectories of furnace temperatures which optimally realize the desired heat inputs into the slabs. The iterative algorithm accounts for constraints on system inputs as well as states and may be used for open-loop control or as a feedforward branch in two-degrees-of-freedom control structures. The feasibility and the limitations of the approach are demonstrated by means of an example problem. © 2010 Elsevier Ltd. All rights reserved.

Steinboeck A.,Vienna University of Technology | Wild D.,AG der Dillinger Huttenwerke | Kiefer T.,AG der Dillinger Huttenwerke | Kugi A.,Vienna University of Technology
International Journal of Heat and Mass Transfer | Year: 2010

A mathematical model of the reheating process of steel slabs in industrial fuel-fired furnaces is developed. The transient temperature field inside the slabs is computed by means of the Galerkin method. Radiative heat transfer inside the furnace constitutes boundary conditions that couple the dynamic subsystems of the slabs. Constraining the heat fluxes to piecewise linear, discontinuous signals furnishes a discrete-time state-space system. Conditions for an exponential decrease of the open-loop control error are derived. Measurements from an instrumented slab in the real system demonstrate the accuracy of the model. The simple and computationally inexpensive model is suitable for trajectory planning, optimization, and controller design. © 2010 Elsevier Ltd. All rights reserved.

Kiefer T.,AG der Dillinger Huttenwerke | Graichen K.,Vienna University of Technology | Kugi A.,Vienna University of Technology
IEEE Transactions on Control Systems Technology | Year: 2010

This brief deals with the tracking control design of a helicopter laboratory experimental setup. In order to be able to realize highly dynamic flight maneuvers, both input and state constraints have to be systematically accounted for within the control design procedure. The mathematical model being considered constitutes a nonlinear mathematical mechanical system with two control inputs and three degrees of freedom. The control concept consists of an inversion-based feedforward controller for trajectory tracking and a feedback controller for the trajectory error dynamics. The design of the feedforward controller for a point-to-point flight maneuver is traced back to the solution of a 2-point boundary value problem in the Byrnes-Isidori normal form of the mathematical model. By utilizing special saturation functions, the given constraints in the inputs and states can be systematically incorporated in the overall design process. In order to capture model uncertainties and external disturbance, an optimal state feedback controller is designed on the basis of the model linearization along the desired trajectories. The proposed control scheme is implemented in a real-time environment, and the feasibility and the excellent performance are demonstrated by means of experimental results. © 2009 IEEE.

Steinboeck A.,Vienna University of Technology | Wild D.,AG der Dillinger Huttenwerke | Kugi A.,Vienna University of Technology
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2011

A Lyapunov-based MIMO state feedback controller is developed for slab temperatures in a continuous, fuel-fired reheating furnace. Following an early lumping approach, the computationally simple tracking controller is designed for a nonlinear, switched dynamic model that captures both conductive and radiative heat transfer. The controller modifies reference trajectories of furnace temperatures and is part of a cascade control scheme. Given some nonrestrictive conditions, exponential stability is ensured, even under non-steady state operating conditions. The capabilities of the controller are demonstrated by means of an example problem. © 2011 IFAC.

Bruckhaus R.,AG der Dillinger Huttenwerke | Fandrich R.,Stahlinstitut VDEh
Transactions of the Indian Institute of Metals | Year: 2013

Abstract: About 60 % of the crude steel in Europe is currently produced by the oxygen steelmaking process and 40 % by the electric steelmaking process. The product range is of decisive importance for the layout of the steelworks and the equipment for secondary metallurgical treatment. Regarding steelmaking worldwide, thin slabs are increasingly being produced in addition to conventional formats such as slabs, blooms, billets and beam blanks. In order to ensure long-term economic success, however, companies have continuously to develop sophisticated technologies for steel production. Challenges for the future remain in the production of high-purity steel grades, as well as the development of zero-error strategies with maximum productivity and flexibility. This paper summarizes current trends in the development of steelmaking processes. © 2013 Indian Institute of Metals.

Bambach M.,RWTH Aachen | Seuren S.,AG der Dillinger Huttenwerke
Journal of Materials Processing Technology | Year: 2015

In multi-pass rolling processes such as plate rolling, accurate predictions of roll force and torque over all roll passes are desired, so that the pre-calculated roll pass schedule can be put into practice without exceeding the limits of the roll stand. In this context, the grain size has two roles; the final grain size determines the product properties, and the evolution of grain size influences the force predictions. Since the grain size predicted after each roll pass enters the recrystallization kinetics and grain size evolution equations of the subsequent pass, a feed-back loop for the grain size calculation is created, which may become unstable so that the computed roll force and grain size become very sensitive to small variations in the input parameters. Although models for the evolution of grain size in multi-stage hot rolling have been applied in the industry for decades, their mathematical stability has not been given much attention, which poses difficulties for force and grain size predictions in cases subject to partial recrystallization. In this paper, the stability of a common semi-empirical model for static recrystallization and grain growth is investigated. The conditions under which instabilities occur are analyzed both for an industrial plate rolling pass schedule and for idealized load cycles. It is shown that complete recrystallization between roll passes leads to a stable grain size evolution, and that some states of partial recrystallization are unstable and hence problematic for force and grain size predictions. Instabilities in force and grain size predictions of an industrial pass schedules are analyzed by computing sensitivities using automatic differentiation of the model, showing that large amplification factors may occur if the states of partial recrystallization are treated by average strains and grain sizes. The instabilities are an inherent property of the closed-form equations for microstructure evolution for some states of partial recrystallization. However, the side effects of the instabilities can be reduced if the microstructure is not represented by average values of grain size and accumulated strain but by substructures generated by partial recrystallization. This way, the accuracy of roll force predictions can be considerably improved. © 2014 Elsevier B.V.

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