Dissolution of hardening phases during deformation in an A6061 Aluminium alloy

The temperature limit for the technological usage of an A6061 aluminium alloy is investigated taking into account the initial precipitation state and the stability of hardening phases during the deformation process. In a critical temperature range, the dissolution of precipitates occurs parallel to deformation processes resulting in a characteristic strain rate-dependent shape of the stress strain curve. In the present contribution, we introduce a new tool for the comprehensive representation of precipitate dissolution in the form of dissolution maps. Starting from an initial precipitation state, the phase fraction evolution for hardening phases is modelled with the thermokinetic software package MatCalc for a series of deformation temperatures. The resulting diagram shows contour lines of constant phase fraction over temperature and time, depicting a critical region where precipitate dissolution represents a crucial microstructural mechanism for strength evolution. The modelling results are validated on a series of compression tests on a Gleeble 1500 thermo-mechanical simulator, where the samples are artificially aged and tested at different strain rates.