Étude de la stabilité microstructurale des matériaux de structure industriels durant les traitements thermiques et thermomécaniques compliqués.

Abstract

This work is a contribution to the understanding of the phenomena occurring during the continuous heating of an Al-Mg-Si alloy plastically deformed. Thus, the effect of plastic deformation at two temperatures (cold and 100°C), applied after two heat treatments, on the precipitation sequence occurring during continuous heating, has been investigated. In order to follow the microstructure evolution during the applied treatments, several techniques have been used such as differential scanning calorimetry (DSC), X-rays diffraction (XRD), differential dilatometry, optical microscopy, SEM, microhardness and internal friction measurements. The obtained results showed that the heat treatments used as well as the plastic deformation applied lead to the modification of the precipitation sequence of the alloy, which has been interpreted by the interactions between precipitation, recovery and recrystallization reactions, the improvement of their mechanical properties and in particular the microhardness values.