Strain rate sensitivity of the commercial aluminum alloy AA5182-O

The mechanical behavior of the commercial aluminum alloy AA5182-O is investigated at temperatures ranging from -120 to 150 °C and strain rates from 10^-6 to 10^-1 s^-1. The strain rate sensitivity parameter is determined as a function of temperature and plastic strain, and the strain rate and temperature range in which dynamic strain aging leads to negative strain rate sensitivity is mapped. The effect of dynamic strain aging on ductility and strain hardening is investigated. The sensitivity of the measured quantities to the experimental method employed and their dependence on grain shape are discussed. The experimental data are compared with the predictions of a model constructed based on a recently proposed mechanism for dynamic strain ageing. The mechanism is based on the effect solute clustering at forest dislocations has on the strength of dislocation junctions. The model is shown to reproduce qualitatively the experimental trends.