The Influence of Annealing on Microstructure and Microhardness of Twin-roll Cast Al-Mg-Sc-Zr Alloy

M. Cieslara, J. Bajera, M. Šlapákováa, B. Křivskáa, M. Ziminab, M. Stolbchenkoc, O. Grydinc aCharles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2, Czech Republic bResearch Center Rez, Hlavní 130, 250 68 Husinec-Řež, Czech Republic cUniversity Paderborn, Faculty of Mechanical Engineering, Pohlweg 47-49, 33098 Paderborn, Germany

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Twin-roll casting is an effective and energy-saving method enabling direct preparation of strips of the requested final thickness. However, due to high solidification rates and higher solid solution supersaturation a significantly different microstructure is formed in comparison with conventionally cast alloys. Recently, the Sc and Zr containing aluminum alloys are considered to be new advanced materials for the transportation industry. The influence of Sc and Zr on mechanical properties of twin-roll cast Al-Mg alloy was investigated in the present study. A significant effect of Sc and Zr on hardening of the material after annealing in temperature interval between 250° and 400° was confirmed. Maximal hardness was obtained after two hours of annealing at 300° due to precipitation of a fine dispersion of Sc and Zr containing precipitates. Exposure of the annealed material to higher temperatures results in a partial degradation of mechanical properties due to changes of the strengthening effect of precipitates. However, a partially positive role of remaining precipitates, hindering recrystallization, persists even up to 550°.

DOI:10.12693/APhysPolA.134.145 topics: aluminum alloy, twin-roll casting, microhardness