Simulation and experimental analyses of dynamic strain aging of a supersaturated age hardenable aluminum alloy

In this paper, dynamic strain aging (DSA) behavior in a temperature range of (25-235 degrees C) and strain rate range of (10(-4)-5 x 10(-2) s(-1)) was investigated using a supersaturated age hardenable aluminum alloy. It was found that two mechanisms consisted of pinning of solute atoms to mobile dislocations and dynamic precipitation, were responsible for DSA in the testing conditions. The effects of both mechanisms on the macroscopic flow curve were studied using experimental and improved physically based material modeling approaches. It was shown that both phenomena lead to a negative strain rate hardening in the alloy. Dynamic precipitation acting at high temperature results in considerable work hardening and material strengthening. Taking into account these microstructural phenomena, the effects of deformation temperature and strain rate on the macroscopic flow behavior were discussed. The proposed modeling approach could successfully predict the experimental flow curve, possible jerky flow, and the corresponding serration types. Also, the spatial nucleation and propagation of the localized deformation bands along the specimen gauge length were recorded by a digital image correlation method and compared with the proposed model predictions. (C) 2013 Elsevier B.V. All rights reserved.