Study on dynamic strain aging phenomenon of 3004 aluminum alloy

3004 Aluminum alloy has been subjected to tension test at a range of strain rates (5.56 × 10−5 to 5.56 × 10−3 s−1) and temperatures (233–573 K) to investigate the effect of temperature and strain rate on its mechanical properties. The serrated flow phenomenon is associated with dynamic strain aging (DSA) and yield a negative strain rate dependence of the flow stress. In the serrated yielding temperature region a critical transition temperature, Tt, was found. The critical plastic strain for the onset of serrations has a negative or positive temperature coefficient within the temperature region lower or higher than Tt. According to the activation energy, it is believed that the process at the temperature region lower than Tt is controlled by the interaction between Mg solute atom atmosphere and the moving dislocation. In the positive coefficient region, however, the aggregation of Mg atoms and precipitation of second phase decrease the effective amount of Mg atoms in solid solution and lead to the appearance of a positive temperature coefficient of the critical plastic strain for the onset of serrations.