Effects of high Mg content and processing parameters on Portevin-Le Chatelier and negative strain rate sensitivity effects in Al–Mg alloys

Portevin-Le Chatelier (PLC) effect arises with increasing the Mg content in Al–Mg alloys. Due to the PLC effect, instability in plasticity and negative strain rate sensitivity (nSRS) are encountered during the metalworking process of the Al–Mg alloys, which reduce the ductility and formability of the materials. Herein, torsion tests are performed on the Al–Mg alloys with high Mg content to determine the effect of Mg content and processing parameters on the PLC and nSRS effects. Analyses of the flow curves and deformed microstructures reveal that the Mg content and processing parameters affect the dynamic strain aging and PLC effects in Al–Mg alloys. In some combinations of Mg content, temperature, and strain rate, the PLC effect is weakened and nSRS is not observed because the appropriate selection of Mg content and temperature can lower the stacking fault energy of Al–Mg alloy.