Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 29: Microstructure and Phase Transformations
MM 29.1: Talk
Wednesday, April 3, 2019, 15:00–15:15, H46
Abnormal grain growth in friction stir welded aluminium with zirconium additives — •Moritz Winter1, Maximilian Gnedel1, Amanda Zens2, Ferdinand Haider1, and Michael F. Zäh2 — 1Chair for Experimental Physics I, University of Augsburg, Universitätsstraße 2, 86159 Augsburg (Germany) — 2Institute for Machine Tools and Industrial Management, Technical University of Munich, Boltzmannstraße 15, 85748 Garching (Germany)
Friction Stir Welding (FSW) is a well-established solid-state joining process for materials such as aluminium. In Al-Li-Cu alloys, such as AA2195 aluminium, abnormal grain growth (AGG) can be a crucial issue during post-processing of the produced welds, whilst the alloy contains zirconium for grain boundary stabilisation. Both, the microstructural stability during subsequent heat treatment as well as the mechanical properties in general can be optimized by intermixing specific micrometer-sized metal powders as well as metal foils. By dispersing additional zirconium powder inside a matrix of AA2195 aluminium during FSW, the formation of abnormal grains can be reduced, if suitable processing parameters are used. Using optical microscopy, the reduction of the secondary recrystallized area can be revealed. In addition, the formation of intermetallic phases, acting as pinning particles to hinder AGG, can be evaluated using transmission electron microscopy (TEM). Furthermore, electron backscatter diffraction (EBSD) provides insights on the changes of the crystallographic texture of the welding regions both post-weld and after subsequent heat treatment.