The deformation behaviour of AA6111 as a function of temperature and precipitation state

Tensile tests were conducted on the aluminum alloy, AA6111, over a range of test temperatures from 4.2 to 293 K. The state of precipitation was also varied with tests on material in the supersaturated solid solution, after 1, 6 h and 6 months at 180°C. The work hardening behaviour was quantified by numerically differentiating the data from tensile tests. In addition, strain rate change tests were conducted during tensile tests at 77 K. It was observed that the work hardening behaviour was a strong function of test temperature and precipitation condition. In particular, it was found that the supersaturated solid solution showed particularly high work hardening characteristics. For the samples aged for 1 and 6 h, a high initial work hardening rate was observed followed by a rapid drop in the hardening rate. Finally, for the overaged material, it was observed that the hardening rate decreased at a higher rate than high purity aluminum. Strain rate change data showed that for the obstacles formed in the early stages of ageing, thermal activation was important, while for overaged conditions, thermal activation became less significant. This was attributed to the change in the precipitate characteristics during ageing.