Abstract
Various deformation mechanisms may contribute to the high temperature plastic deformation of twin-roll cast AlMg3 (AA5754) sheets. The evaluation of the strain rate sensitivity parameter m suggested that grain boundary sliding, which is generally responsible for superplastic behaviour, might be operating at certain temperature and strain rate conditions. The investigation of the surface relief of samples strained at various deformation conditions was carried out using atomic force microscopy. Both grain boundary sliding and dislocation slip were observed. Grain boundary sliding was accompanied by intensive cavitation that prevented the material from reaching superplastic values of ductility.

Key words
AA5754 sheet, twin-roll casting, grain boundary sliding, atomic force microscopy, cavitation

Full text (571 KB)