In the present work, the role of Mg atoms in the form of either Mg clusters or β phase on the moving dislocations in 5083 aluminum alloy sheet were investigated by comparing the plastic flow behavior and Portevin-Le Chatelier (PLC) character in annealed and quenched conditions. It is found that the tensile strength of quenched sheets at different strain rates is slightly higher than those under annealed condition while the yield strength at both conditions is similar. In annealed sheets, the yield plateau was clearly observed at all tested strain rates with a strain less than 0.012, and its width increased with the increasing strain rate. However, no yield plateau was observed in quenched sheets. On the other hand, the characters of PLC are greatly varied with applied conditions and strain rate. Generally, annealed sheets have a higher waiting time, but lower critical strain/stress at lower strain rate (~1 × 10-4 s-1), but they are similar at a higher strain rate (1 × 10-2 s-1). However, the falling time at both annealed and quenched conditions are almost the same at tested strain rates.
Keywords: 5083 aluminum alloy; PLC characteristic; annealed; quenched; strain rate.