High temperature mechanical properties of an aluminum alloy containing Zn and Mg

This paper studies the high temperature mechanical properties of as-cast Al–Zn–Mg using tensile and creep testing. Hot tensile tests were performed in the temperature and strain rate ranges of 350–400 °C and 10−5 to 10−3 s−1 respectively. Creep tests were carried out under constant load with initial stress ranging from 5 to 22 MPa, at 350 and 400 °C. The alloy exhibits class A creep behavior, due to the viscous glide of dislocations. The tensile flow curves, corrected to account for the effect of sample elongation on strain rate, also show a decline in stress commonly observed in Al–Mg alloys. The highest ductility and strain rate sensitivity were both observed for strain rates ranging from 10−5 to 10−4 s−1. During hot deformation the alloy exhibits cavitation which increases with temperature. The analysis of these phenomena has shown that cavity growth is mainly controlled by plastic strain.