Effect of Friction Stir Processing on the Microstructure and Mechanical Properties of Thick Al-6061 Alloy

This paper highlights the influence of severe thermomechanical processingSevere thermomechanical processing conditions on fabricating a high-strengthStrength and tough, 12 mm thick aluminum alloyAluminum alloys (Al-6061-T6). An optimum thermomechanical condition using friction stir processing (FSP)Friction stir processing (FSP) resulted in a material with better tensile propertiesTensile properties and a fivefold increase in impact toughnessImpact toughness. Detailed characterizationCharacterization revealed the evolution of a refined microstructureMicrostructure with a uniform distribution of second-phase particles. Grain size variation at different processing conditions is examined to identify the mechanismsMechanisms of microstructural evolution. The tensile sample with 100% processed material fails at a location of refined microstructureMicrostructure and inhomogeneous deformation features. The improved tensile strengthTensile strength and toughness of the processed zone are attributed to homogeneous deformation, recrystallized microstructureMicrostructure evolution, grain refinementGrain refinement, and quality of processed zone to absorb energy, homogeneous distribution of precipitates, and location of the fractureFracture in the stir zone.