Effect of Friction Stir Welding Parameters on Microstructure and Properties of Welded 5083 Aluminium Alloy

The friction stir welding (FSW) parameters were designed in this study by orthogonal experimental method. The microstructure, mechanical properties and corrosion behavior of corresponding FSW joints of 5083 aluminium alloy (AA5083) were also investigated. Scanning Kelvin probe force microscopy (SKPFM) was employed to study local potential differences on the FSW joint. Results showed that the welding parameters greatly influenced the FSW joint properties of the AA5083. The ratio of rotation speed to welding speed (n/v) mainly affected the mechanical properties of the joint. The tensile strength for the joint was reduced when welded with too large or too small n/v. The hardness of all FSW joints was characterized with similar 'W-shaped,' and minimum hardness value appeared on advancing side of the heat affected zone. Different heat input and agitation intensity caused heterogeneous microstructure for the AA5083 FSW joint, which led to differences in passivation properties of weld nugget zone, thermo-mechanically affected zone and heat-affected zone. Susceptibility of the AA5083 FSW joint to pitting corrosion was attributed to the difference of relative potential between the intermetallic phase and Al matrix.