Enhanced mechanical properties of friction stir welded AA2024-T3 via cold spraying

Abstract: The microstructural evolution of 3.2mm friction stir welded (FSWed) AA2024-T3 joints during cold spraying (CS) and its effect on mechanical properties were investigated by a combination of electron back-scattered diffraction, differential scanning calorimetry and mechanical tests. The frictional heat and mechanical stirring during FSW resulted in large inhomogeneities in microstructure and low mechanical properties of FSWed joint. After depositing an aluminium coating on the joint, the hardness recovered in the stir zone and two low hardness zones due to the increase in number densities of Guinier-Preston-Bagaryatsky (GPB), whilst there was obvious change in the microstructure. The tensile properties of FSWed AA2024-T3 joints was clearly enhanced by the aluminium coatings. The two effects of "shot peening effect (SPE)" and "heat flow effect (HFE)" during CS were employed aiming at illustrating the mechanism of enhanced mechanical properties. Keywords: Friction stir welding; Cold spraying; Microstructure; Mechanical properties;