Radiography and Corrosion Analysis of Sub-merged Friction Stir Welding of AA6061-T6 Alloy

Friction Stir Welding (FSW) is considered to be the most significant development in metal joining in recent decades. In this investigation, the quality and corrosion behavior of a submerged friction stir welded sample of AA 6061-T6 alloy were studied. This paper examines the three parameters used for this process such as rotational speed (rpm), welding speed (mm/min) and water level (mm). Visual inspection, X-ray radiography, micro-structural evolution and corrosion testing were employed to analyze the welded samples. A total of three levels (low, medium and high) were used for rotational speed (rpm) and welding speed (mm/min), each along with three varying water levels (mm) for radiography and corrosion analysis of the nine samples. No defects were observed on the weld region via visual inspection. Radiography tests indicate various defects in the welded samples with higher water level as its parameter. The interfacial and nugget region of the welded sample was also studied for the defect free sample evaluated by radiography technique, using Scanning Electron Microscope (SEM), showing no defects, good mixing and re-crystallized structure. The corrosion rates of the welded samples were studied via polarization in 3.5% Na-Cl solution, showing a high corrosion rate for samples with higher water level as their parameter.