  The microstructure, mechanical properties, and corrosion behavior of friction
stir welded (FSW) AA6061 aluminum alloys were investigated. Dynamic
recrystallized structures were observed and grain sizes of nugget zone (NZ),
thermomechanically-affected zone (TMAZ), heat-affected zone (HAZ), and base
material (BM) were different. Hardness test indicated that the minimum and
maximum hardness values wereobtained in the HAZ and BM, respectively. Tensile
results showed that fracture occurred in the relatively weak regions in between
TMAZ and HAZ. Polarization tests illustrated that the FSW process improved the
corrosion resistance of AA6061-AA6061 and the HAZ had better corrosion
resistance than other regions. Raman characterizations revealed that aluminum
hydroxide was the main corrosion product formed on Al after immersion
experiments. Intergranular attack was observed in the NZ and downside by
scanning electron microscopy.
