High temperature impact deformation and dislocation substructure of 6061-T6 aluminum alloy

The high temperature deformation behaviour of 6061-T6 aluminum alloy is investigated at strain rates ranging from 1×10³~5×10³ s^-1 and temperatures of 100~350°C using a compressive split-Hopkinson pressure bar system. It is found that the flow stress, work hardening rate and strain rate sensitivity all increase with increasing strain rate or decreasing temperature. Moreover, the temperature sensitivity increases with increasing strain rate and increasing temperature. The activation energy varies as a function of the strain rate and temperature and has a maximum value of 64.8 kJ/mol under the present loading conditions. The dislocation density increases, and the cell size decreases, as the strain rate is increased or the temperature decreased. The change in the dislocation density and cell size causes a corresponding change in the flow stress.