A doctoral defence in the times of Corona
Despite the restrictions on everyday university life associated with the COVID 19 pandemic, the WOT succeeded in defending its doctorate in accordance with the rules. On 8 July 2020, Lisa Winter convinced the attending reviewers as well as the digitally connected colleagues, friends and family members with her thesis on „Fatigue strength and medium-voltage sensitivity of the alloy AlMgSi1 after high-grade plastic forming and anodic or plasma-electrolytic oxidation“.
After passing the non-public revision, Ms Winter gave a lecture on the possibility of using conversion treatment to increase the reduced fatigue strength of highly plastically formed aluminium materials with the help of the Big Blue Button conference system at Chemnitz University of Technology. In order to open up this combination for technically relevant applications, sound research into the mutual relationships between substrate material, conversion layer and the resulting range of properties of the substrates under cyclic loading was necessary. The influence of the conversion layer type on the fatigue strength and the cracking behaviour had so far only been insufficiently investigated and especially in combination with a highly plastically formed substrate. In her work, Ms Winter investigated the frequently used wrought aluminium alloy EN AW-6082 (AlMgSi1). The highly plastic forming was achieved using the Equal-Channel Angular Pressing (ECAP) process available at IWW. The fatigue strengths in the so-called HCF range (High Cycle Fatigue) of anodic, hard anodic and plasma-electrolytic conversion treatments of surfaces of different ECAP-treated and undeformed states of the selected substrate material were then compared. The present work thus provides an important contribution to the understanding of the complex relationships between the structure of the conversion layer, the microstructural states and properties of the substrate material and the resulting fatigue strength as a function of the applied medium voltage.
The work was published under the IWW's own publishing house in the series „Werkstoffe und werkstofftechnische Anwendungen“ (Volume 87, ISBN 978-3-949005-01-5).
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Prof. Lutz Krüger (second reviewer), Dr. Lisa Winter, Prof. Thomas Lampke (doctoral supervisor and 1st reviewer) and Prof. Guntram Wagner (head of the doctoral procedure)
30.7.2020 – Personnel of the professorship ( thomas.grund@mb… )
