Papers by Author: Anke Pyzalla

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Authors: Haroldo Pinto, Anke Pyzalla, Heinz Hackl, Jürgen Bruckner
Abstract: Recently a new welding technique, the so-called ‘Cold Metal Transfer’ (CMT) technique was introduced, which due to integrated wire feeding leads to lower heat input and higher productivity compared to other gas metal arc (GMA) technique. Here microstructure formation and residual stress state in aluminum CMT welds are characterized and compared to those produced by pulsed MIG- and Laser-hybrid techniques. The results show a small heat affected zone (HAZ) in the MIG weld, the HAZ in the CMT and the laser hybrid welds was not visible by optical and scanning electron microscopy. Compared to the MIG welding the CMT process appears to introduce slightly smaller maximum tensile residual stresses into the weld.
Authors: H.M. Mayer, Anke Pyzalla, Walter Reimers
Authors: Claudia Juricic, Haroldo Pinto, Thomas Wroblewski, Anke Pyzalla
Abstract: Mass gain during oxidation, texture and residual stresses in oxide layers on polycrystalline Armco iron substrates with different surface conditions are investigated using thermogravimetry microscopy and synchrotron X-rays. The mass gain during oxidation in all samples follows a parabolic law. The parabolic oxidation constant increases with increasing roughness of a mechanically ground respectively polished oxide layer. Electrolytic polishing (grain surface etching) reduces while grain boundary etching increases the parabolic oxidation constant compared to the mechanically polished sample. All oxide layers show columnar growth of the magnetite and a moderate fiber texture. The magnetite contains compressive residual stresses. Under the conditions chosen for the oxidation treatment the magnitude of these compressive residual stresses does not depend on the substrate surface condition.
Authors: Pedro Brito, Haroldo Pinto, André Rothkirch, Anke Pyzalla
Abstract: The evolution of phase composition and growth stresses in oxide scales growing on the polycrystalline Fe-15at.%Al alloy at 700°C in air was studied by in-situ synchrotron X-ray diffraction and X-ray photoelectron spectroscopy. The oxidation kinetics was determined by thermogravimetry. The results showed that, under these conditions, metastable -Al2O3 appears only during the first minutes of oxidation and the main oxides formed since the early oxidation are -Al2O3 and -Fe2O3. High volume fractions of -Fe2O3 caused accelerated oxidation rates in the first hours. -Al2O3 and -Fe2O3 grow epitaxially, evolving compressive and tensile growth stresses, respectively.
Authors: Anke Pyzalla, J. Wegener, Klaus B. Müller, Klaus Dieter Liss
Authors: Anke Pyzalla, Bjoern Reetz, J. Wegener, Alain Jacques, Olivier Ferry, J.-P. Feiereisen, Thomas Buslaps
Authors: K. Holler, Bjoern Reetz, Klaus B. Müller, Anke Pyzalla, Walter Reimers
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