Author(s)

A. May, M. A. Belouchrani & A. Britah

Abstract

In the present work, the effects of heat treatments on the evolution of oligocyclic fatigue damage on two types of aluminium alloys were studied. The two alloys are largely used in the aircraft industry because of their good mechanical characteristics and their lightness. The main factor influencing damage of these two types of alloys is decohesion of interfaces in Al-Si, Al-Cu and Al-Mg particles resulting from the stress concentration in these interfaces. Our work is to repair this decohesion by the use of specific heat treatments. The monitoring of the damage evolution is done by using the variation of electrical resistivity resulting from the microstructure transformations; this change of the microstructure is due to the variation of different parameters of annealing heat treatment. This method allowed us to find the best parameters of the heat treatments to use during repair. Those parameters are: temperature, maintaining time and speed of cooling. The idea of using heat treatments is based on the role of those heat treatments on the microstructure of material, on its behaviour before and after the first stage of fatigue damage. From this viewpoint, we had to make the microcavities created during the fatigue damage decrease; it will be only a contribution to the regeneration of the initial properties before this damage. The results obtained showed that the regeneration of the initial properties of the material after fatigue damage is possible with appropriate heat treatments and optimal treatment exists if a certain threshold of damage is not reached. Finally, this process can be envisaged to increase the fatigue life of components when these are submitted to fatigue loading. Keywords: fatigue damage, heat treatment, aluminium alloys, electrical resistivity and microstructure.

Keywords

fatigue damage, heat treatment, aluminium alloys, electrical resistivity and microstructure