Influence of Alclad layers on mechanical properties of friction stir welded 2024-T3 aluminium alloy thin sheets
Résumé
Alclad sheets are used in aeronautics to resist corrosion. This paper presents the investigation of the effect of the Alclad on the mechanical properties of thin friction stir welds of 2024-T3 aluminium alloy (3 mm and 1 mm). The friction stir welding process is carried out on sheet metal without any surface preparation. Tensile tests, micro-hardness measurements, optical microscopy and scanning electron microscopy observations are performed to identify the behaviour of the friction stir welds at local and macroscopic scales. The evolution of micro-hardness through the welds associated with literature results reliably describe precipitates in each area of the welds. Tensile test results combined with micrographic observations reveal that the Alclad layer is introduced by the pin into the alloy in a pointed shape. The weld fractures are clearly located in Alclad insertion zones. Independently of the state of the precipitates due to the friction stir welding parameters, Alclad insertions are responsible for the decrease in ductility of the welds.
