Welding of Al-Zn-Mg alloys is increasingly used in the transportation industry. The optimisation of the welding process requires a good understanding of the microstructures generated by the rapid temperature rise in the heat-affected zone.
This study deals with the evolution of the precipitation state after welding of the 7108.50 alloy in different initial tempers. A quantitative characterisation of the hardening precipitates in the heat-affected zone has been carried out by SAXS, TEM and DSC just after welding and after different post-welding heat treatments. To better understand the mechanisms involved in the precipitation evolution during this highly non-isothermal thermal cycle, controlled heat treatments, including reversion and continuous heating, have been studied.
Modelling based on the evolution of a particle distribution has been developed in order to predict the precipitation state after various heat treatments, including welding.