Assessment of the friction stir welding parameters effect on mechanical properties and defect formation in 10 mm thick AA5056 alloy welded joints

Abstract

In this work, welded joints produced by the friction stir welding were investigated. The selection of technological parameters for the non-heat-hardenable aluminum-magnesium alloy AA5056 was performed. The welding workpiece thickness was 10 mm. Structural and strength characteristics were studied, as well as the presence or absence of defects in friction stir welded joints depending on a welding mode. Carried out tests indicate that during the friction stir welding of 10 mm thick samples under varying conditions there is the formation of a characteristic complex structure in the stir zone since heat dissipation and plastic deformation causes significant changes in the microstructure and properties of welded joints. The strongest joint has an ultimate tensile strength of 303 MPa, which exceeds the strength of the base metal by 2 MPa. Only 3 out of the 32 used modes do not allow to produce welds with a strength exceeding 0.9 from the base metal ultimate tensile strength. Carried out researches have allowed revealing a range of optimum friction stir welding parameters, providing joints with required properties.