Influence of homogenization on the microstructure, mechanical properties and texture of the twin-roll cast AA8006 sheet processed by accumulative roll-bonding

¹ Charles University, Faculty of Mathematics and Physics, Department of Physics of Materials, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
² Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Department of Materials, Trojanova 13, 120 00 Prague 2, Czech Republic
³ Czech Aerospace Research Centre, Beranových 130, 199 05 Prague 9 – Letňany, Czech Republic
⁴ COMTES FHT a.s., Průmyslová 995, 334 41 Dobřany, Czech Republic
⁵ Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Department of Solid-State Engineering, Trojanova 13, 120 00 Prague 2, Czech Republic

^* Corresponding author: Miroslav.Karlik@fjfi.cvut.cz

Abstract

Unhomogenized and homogenized AA8006 (Al-Fe-Mn-Si) alloy sheets twin-roll cast to strip 8.5 mm thick, processed by accumulative roll-bonding (ARB) on 2 mm thick sheets up to 6 cycles were studied. The microstructure was characterized by means of scanning and transmission electron microscopy and electron backscattered diffraction (EBSD), mechanical properties were monitored by hardness measurements and tensile tests. The macroscopic texture was determined by X-ray diffraction. The initial texture of the unhomogenized sheet is rotated cubic {001}<110> combined with recrystallization R texture {011}<211>, while the homogenized sheet has a cubic texture {001}<100> with remaining rolling component C {112}<111>. One ARB cycle leads to the formation of low-angle grain boundaries (LAGB) in original coarser grains and to a low angle rotation of the subgrains bounded by LAGB. After the 3rd and 6th ARB cycle unhomogenized and homogenized sheets show a common rolling texture of cold-rolled aluminium. The thermal stability of sheets processed by 6 ARB cycles was tested by isochronal annealing for 30 min up to 450°C. The homogenized sheet starts to recrystallize at 250°C, while the fine grain structure of the unhomogenized sheet is thermally stable up to 400°C.