Microstructure, mechanical properties and corrosion of friction stir welded 6061 Aluminum Alloy

Abstract

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.