Micro- and Macro- Mechanical Properties of Pinless Friction Stir Welded Joints in AA5754 Aluminium Thin Sheets

The effect of process parameters, tool configuration and geometry on FSW of thin sheets in AA5754 aluminium alloy was widely investigated. Tools in "pin" and "pinless" configurations were used. It was shown that the "pinless" tool allows the obtaining of mechanical properties higher than those of the "pin" one. An investigation was also carried out in order to evaluate the microstructure of the joints. Welds obtained with the "pin" tool exhibit a more pronounced grain refinement than the one observed using the "pinless" one even though the presence of cavities and less homogeneity strongly affect the mechanical properties of joints