High ductility and strong work-hardening behavior of Zn modified as-hot-rolled Al-Mg sheets

High ductility combining with relative high strength is of great significance for the application of Al-Mg alloys. In this study, excellent ductility and moderated strength are obtained in the as-hot-rolled Al-9.2Mg-0.5Zn sheet, with ultimate tensile strength (sigma(b)), yield tensile strength (sigma(0.2)) and elongation (delta) are respectively 434 +/- 5 MPa, 228 +/- 2 MPa and 48 +/- 2%. High ductility of the as-hot-rolled Al-9.2 Mg-xZn (0-1.5 wt%) sheets can be ascribed to their strong work-hardening abilities, which increase firstly and then decline with higher Zn content. The highest work-hardening component (n), work-hardening capacity (H-c) and the initial work-hardening rate (theta(0)) in the Al-9.2Mg-0.5Zn sheet are 0.428, 1.793 and 3496 MPa, respectively. The microstructures of the Al-Mg-Zn sheets are characterized by electron backscattered diffraction (EBSD), transmission electron microscope (TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). Low density of pre-existing dislocations (PDs), random grain orientations and reduced stacking fault energy (SFE) contribute to the strong work-hardening capacity and lead to desirable ductility in the as-hot-rolled Al-Mg-Zn sheets. However, numerous precipitates with an uneven distribution are harmful for work-hardening and thus lead to the reduced ductility in the Al-Mg sheet with high Zn content. (C) 2020 Elsevier B.V. All rights reserved.