| 1. |
- Bauer, A., et al.
(author)
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Experimental and numerical investigation on cold flat rolling processes of DC04 sheets with special focus on residual stresses
- 2016
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In: IOP Conference Series. - : Institute of Physics Publishing (IOPP).
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Conference paper (peer-reviewed)abstract
- The process of cold flat rolling is a widespread industrial technique to manufacture semi-finished products, e.g., for the automotive or homewares industry. Basic knowledge of the process regarding dimensioning and adjustment of defined characteristics is already state of the art. However, a detailed consideration and analysis with respect to local inhomogeneous residual stresses in several process steps mostly remains disregarded. A broad understanding of the process due to the distribution of residual stresses in the workpiece and the direction of the stress tensors allows for a definition of the characteristics of the workpiece even before the actual manufacturing process. For that purpose, it is necessary to perform numerical investigations by means of the finite element analysis (FEA) of cold flat rolling processes. Within this contribution, several approaches for the calibration of the FEA with the real flat rolling process will be addressed and discussed. To ensure that the numerical consideration provides realistic results, this calibration is indispensable. General parameters such as geometry, height reduction, rolling temperature, process time, and the rolling speed are considered as well as a photogrammetric survey, and calculated residual stresses with results of X-ray diffraction (XRD) will be compared. In the course of the experiments, a good agreement between the stress results of the FEA and the XRD was found in the center of the specimen. In combination with the allocation of the stress orientations, the agreement close to the edges is also fine. Some issues that cause differences between the FEA and the experiment are dis-cussed.
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| 2. |
- Sieber, Maximilian, et al.
(author)
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Corrosion Protection of Al/Mg Compounds by Simultaneous Plasma Electrolytic Oxidation
- 2015
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In: Materials Today: Proceedings, Volume 2, Supplement 1. - : Elsevier Ltd. ; , s. S149-S155
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Conference paper (peer-reviewed)abstract
- The application of Al/Mg compound materials for lightweight structures is limited by their corrosion susceptibility. The primary corrosion attack takes place at the Mg component. This may partly be caused by galvanic corrosion and partly by the insufficient formation of a natural passive layer on magnesium. Therefore, oxide coatings were produced on the co-extruded Al/Mg compounds by simultaneous plasma electrolytic oxidation (PEO). A silicate-alkaline and a silicate-phosphate-alkaline electrolyte were used for the coincident production of coatings with a thickness of several 10 microns on both the aluminum and the magnesium component. The inherent flaws of the coating (pores, cavities) allow for the infiltration with an epoxy-based sealant. The electrochemical behavior of the magnesium component covered with the oxide coatings with and without sealing was compared with reference to the unmodified surface. The surface modification (PEO w/wo sealing) significantly decreases the corrosion susceptibility of the Mg component, and thus of the compound.
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