|Spoluautoři DOBROŇ Patrik, CHMELÍK František|
The influence of strain rate on the occurrence of plastic instabilities in a cold-rolled AlMg4.5Mn sheet was studied. Heat treated samples were uniaxially loaded in tension at various strain rates and at room temperature (RT). The results are discussed using concurrent acoustic emission (AE) monitoring during mechanical testing and the AE parameters are correlated to the microstructure and to the stress-strain curves in order to better understand the patterns of plastic deformation. All samples exhibited a Lüders band (LB) propagation, which was followed by the Portevin-Le Chatelier (PLC) effect of C, B or A+B band propagation types, dependently on the applied strain rate. Difference in dislocation dynamics of both LB and PLC phenomena is also revealed using the AE response. The formation of LB produces continuous AE signals with relative low amplitudes which are responsible for high AE count rates. The occurrence of the PLC effect is manifested by burst AE signals with high amplitudes resulting in lower AE count rates by comparison to LB.